The present invention relates to an eyeglass lens grinding machine for processing lenses to be fitted in an eyeglass frame.
Eyeglass lens grinding machines are known that process lenses by grinding on the basis of configurational data obtained by tracing the eyeglass frame or template with an eyeglass frame tracer. Some apparatus of this type include edge position detecting means which detects the position of the edge of the lens to be processed on the basis of radius vector information from the eyeglass frame tracer. If the diameter of the lens to be processed is insufficient, the gage head of the edge position detecting means comes out of engagement with the lens, this event is notified to the operator, and then the apparatus stops the subsequent processing steps.
Thus, the conventional eyeglass lens grinding machine is adapted to refrain from processing if the lens to be processed cannot be shaped to completely fit the configuration of the eyeglass frame. However, if the insufficiency of lens diameter is of such a small degree that the tapered edge (bevel) of the lens to be processed is hidden by the peripheral groove of the eyeglass frame, the processing may be performed without any practical problems. In this case, the operator wants to process the lens but finds it impossible to do so with the conventional grinding machine. The need to perform a grinding operation despite the insufficiency of lens diameter will occur most frequently when changing frames and it is a great inconvenience if the grinding operation cannot be performed during frame changing.